package com.hmdp.service.impl;

import com.hmdp.dto.Result;
import com.hmdp.entity.VoucherOrder;
import com.hmdp.mapper.VoucherOrderMapper;
import com.hmdp.service.ISeckillVoucherService;
import com.hmdp.service.IVoucherOrderService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.RedisIdWorker;
import com.hmdp.utils.UserHolder;
import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.aop.framework.AopContext;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.PostConstruct;
import java.util.Collections;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * <p>
 * 服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
@RequiredArgsConstructor
@Slf4j
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {

    private final ISeckillVoucherService seckillVoucherService;
    private final RedisIdWorker redisIdWorker;
    private final StringRedisTemplate stringRedisTemplate;
    private final RedissonClient redissonClient;

    //lua脚本，一加载就会初始化
    private static final DefaultRedisScript<Long> SECKILL_SCRIPT;

    static {
        SECKILL_SCRIPT = new DefaultRedisScript<>();
        SECKILL_SCRIPT.setLocation(new ClassPathResource("seckill.lua"));
        SECKILL_SCRIPT.setResultType(Long.class);
    }

    //阻塞队列
    private BlockingQueue<VoucherOrder> orderTasks = new ArrayBlockingQueue<>(1024 * 1024);

    //线程池
    private static final ExecutorService SECKILL_ORDER_EXECUTOR = Executors.newSingleThreadExecutor();

    @PostConstruct
    private void init() {
        SECKILL_ORDER_EXECUTOR.submit(new VoucherOrderHandle());
    }

    //线程任务：处理订单
    private class VoucherOrderHandle implements Runnable {
        @Override
        public void run() {
            while (true) {
                try {
                    //1.获取队列中的订单信息
                    VoucherOrder voucherOrder = orderTasks.take();
                    //2.创建订单
                    handleVoucherOrder(voucherOrder);
                } catch (InterruptedException e) {
                    log.error("处理订单异常=", e);
                }
            }
        }
    }

    private void handleVoucherOrder(VoucherOrder voucherOrder) {
        //1.获取用户（不能通过线程的方式获取了，因为它是一个新的线程）
        Long userId = voucherOrder.getUserId();
        //创建锁对象
        //分布式锁：Redisson
        RLock lock = redissonClient.getLock("lock:order:" + userId);
        //获取锁
        boolean isLock = lock.tryLock();
        //判断是否成功获取锁
        if (!isLock) {
            //获取失败，返回
            log.error("不允许重复下单");
            return;
        }
        try {
            //执行创建订单
            proxy.createVoucherOrder(voucherOrder);
        } finally {
            //释放锁
            lock.unlock();
        }
    }

    private IVoucherOrderService proxy;
    /**
     * 秒杀下单（异步版）
     *
     * @param voucherId
     * @return
     */
    @Override
    public Result seckillVoucher(Long voucherId) {
        //获取用户
        Long userId = UserHolder.getUser().getId();

        //1.执行lua脚本
        Long result = stringRedisTemplate.execute(
                SECKILL_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(), userId.toString()
        );
        //2.判断结果是否为0
        int r = result.intValue();
        if (r != 0) {
            //2.1 不是0->没有购买资格
            return Result.fail(r == 1 ? "库存不足" : "不能重复下单");
        }
        //2.2 为0->有购买资格，将下单信息保存到阻塞队列中
        long orderId = redisIdWorker.nextId("order");
        // TODO 保存到阻塞队列中

        //3.生成订单
        VoucherOrder voucherOrder = new VoucherOrder();
        //3.1 订单id
        long seckillOrderId = redisIdWorker.nextId("seckill_order"); //这里我是加了前缀
        voucherOrder.setId(seckillOrderId);
        //3.2 用户id
        voucherOrder.setUserId(userId);
        //3.3 代金券id
        voucherOrder.setVoucherId(voucherId);
        //3.4放入阻塞队列
        orderTasks.add(voucherOrder);

        //获取代理对象（事务）
        proxy = (IVoucherOrderService) AopContext.currentProxy();

        //3.返回订单id
        return Result.ok(orderId);
    }


    /**
     * 秒杀下单（同步版）
     *
     * @param voucherOrder
     * @return
     */
    /*@Override
    public Result seckillVoucher(Long voucherId) {
        //1.查询优惠券信息
        SeckillVoucher voucher = seckillVoucherService.getById(voucherId);

        //2.判断秒杀是否开始、结束
        if (voucher.getBeginTime().isAfter(LocalDateTime.now())) {
            //没有开始
            return Result.fail("秒杀尚未开始！");
        }
        if (voucher.getEndTime().isBefore(LocalDateTime.now())) {
            //已经结束
            return Result.fail("秒杀已经结束！");
        }

        //3.判断库存是否充足
        if (voucher.getStock() < 1) {
            //库存不足
            return Result.fail("秒杀库存不足！");
        }

        Long userId = UserHolder.getUser().getId();
        *//*synchronized (userId.toString().intern()) {
            //获取代理对象（事务）
            IVoucherOrderService proxy = (IVoucherOrderService) AopContext.currentProxy();
            return proxy.createVoucherOrder(voucherId);
        }*//*

        //分布式锁：初级
        //创建锁对象
        *//*SimpleRedisLock lock = new SimpleRedisLock("order:" + userId, stringRedisTemplate);*//*
        //分布式锁：Redisson
        RLock lock = redissonClient.getLock("lock:order:" + userId);
        //获取锁
        boolean isLock = lock.tryLock();
        //判断是否成功获取锁
        if (!isLock) {
            //获取失败，返回
            return Result.fail("不允许重复下单");
        }
        try {
            //获取代理对象（事务）
            IVoucherOrderService proxy = (IVoucherOrderService) AopContext.currentProxy();
            //执行创建订单
            return proxy.createVoucherOrder(voucherId);
        } finally {
            //释放锁
            lock.unlock();
        }
    }*/

    /*@Transactional
    public Result createVoucherOrder(Long voucherId) {
        //加：一人一单
        Long userId = UserHolder.getUser().getId();

        //查询订单
        int count = query().eq("user_id", userId).eq("voucher_id", voucherId).count();
        //判断是否存在
        if (count > 0) {
            //用户已经下过单
            return Result.fail("用户已经购买过");
        }

        //4.扣减库存
        *//*boolean success = seckillVoucherService.update()
                                                  .setSql("stock = stock - 1")
                                                  .eq("voucher_id", voucherId)
                                                  .update();*//*
        //4.扣减库存（乐观锁解决超卖问题）
        boolean success = seckillVoucherService.update()
                                               .setSql("stock = stock - 1")
                                               .eq("voucher_id", voucherId)
                                               //                                             .eq("stock", voucher
                                               //                                             .getStock())
                                               //                                             太过小心，导致成功率太低
                                               .gt("stock", 0)  //只要库存大于0，都可以减库存
                                               .update();

        if (!success) {
            //扣减失败
            return Result.fail("扣减失败，库存不足");
        }

        //5.生成订单
        VoucherOrder voucherOrder = new VoucherOrder();
        //5.1 订单id
        long seckillOrderId = redisIdWorker.nextId("seckill_order"); //这里我是加了前缀
        voucherOrder.setId(seckillOrderId);
        //5.2 用户id
        voucherOrder.setUserId(userId);
        //5.3 代金券id
        voucherOrder.setVoucherId(voucherId);
        //5.4 订单写入数据库
        save(voucherOrder);

        //6.返回订单id
        return Result.ok(seckillOrderId);
    }*/

    @Transactional
    public void createVoucherOrder(VoucherOrder voucherOrder) {
        //一人一单
        Long userId = UserHolder.getUser().getId();

        //查询订单
        int count = query().eq("user_id", userId).eq("voucher_id", voucherOrder.getVoucherId()).count();
        //判断是否存在
        if (count > 0) {
            //用户已经下过单
            log.error("用户已经购买过");
            return;
        }

        //4.扣减库存（乐观锁解决超卖问题）
        boolean success = seckillVoucherService.update()
                                               .setSql("stock = stock - 1")
                                               .eq("voucher_id", voucherOrder.getVoucherId())
                                               .gt("stock", 0)  //只要库存大于0，都可以减库存
                                               .update();

        if (!success) {
            //扣减失败
            log.error("扣减失败，库存不足");
            return;
        }

        //5.4 订单写入数据库
        save(voucherOrder);
    }
}
